The present invention relates to a measuring device for contactless control of a design of metallic structural elements, preferably helical structural elements, provided with at least one coil through which an alternating current flows.
Measuring devices of the above mentioned general type are known in the art. In known measuring devices the design of structural elements, for example screws, is determined by coils through which high frequency alternating current flows. The measuring principle is based on a change in the impedance of the coil when the shape of the structural element changes. The coils of the above mentioned devices are formed as flat coils. Such devices have some disadvantages. During measurements of relatively long screw thread when the whole thread length is desired to be controlled, the coils must have a rectangular or an oval shape. As a result, the construction of the coils is expensive and their manufacture is quite costly.